pkg/front_end/parser_testcases/declaring_constructors/declaring_parameter.dart

class C() {}
class C(a) {}
class C(a b) {}
class C(var a) {}
class C(final a) {}
class C(var a b) {}
class C(final a b) {}

enum E() {}
enum E(a) {}
enum E(a b) {}
enum E(var a) {}
enum E(final a) {}
enum E(var a b) {}
enum E(final a b) {}

extension type ET() {}
extension type ET(a) {}
extension type ET(a b) {}
extension type ET(var a) {}
extension type ET(final a) {}
extension type ET(var a b) {}
extension type ET(final a b) {}